1. Field of the Invention
This invention relates to an apparatus for controlling travelling of a vehicle by transmitting signals to the vehicle travelling on a track by means of signal lines disposed along the track.
2. Description of the Prior Art
In vehicle travelling apparatus of this kind, it is desired to make a diversity of travelling control of a vehicle possible by means of a small number of signal lines.
In conventional vehicle travelling apparatus of this type, for example, as shown in the Japanese patent publication No. 56-21627 (1981), a speed command signal for commanding the travelling speed of a vehicle is coded and transmitted to the vehicle by wireless (radio) control, and thereby the travelling of the vehicle is controlled. Also, apart from the above-described control, three or four signal lines are installed on or near the track on which the vehicle travels and the speed command signal is transmitted from these signal lines to the vehicle and thereby the vehicle is controlled for its travelling.
However, in the above-described conventional technology, the speed command signal is required to be coded, and therefore a problem occurs in that a circuit configuration of a transmitting unit for outputting the speed command signal becomes complicated, and accordingly the whole apparatus becomes expensive.
Also, another problem occurs that, in the case where the vehicle receives a signal different from the original speed command signal due to effect of external noise, the vehicle suddenly starts or stops, or further travels at an unexpected speed.
Furthermore, three or four signal lines are required to be disposed along the track, and therefore a disadvantage exists in cost.